Patent KR-100800081-B1 (KR)
Title: Hydraulic circuit of option device of excavator
Inventor: JEON MAN SUK
IPC: E02F3/42
Filed: 2006-08-29
Granted: 2008-02-01
Abstract: A hydraulic circuit of an option device for an excavator is provided to improve operatability by supplying hydraulic fluids to an option device regularly regardless of the size of load occurring in an option device, to regulate hydraulic fluids required for various kinds of option devices respectively, and to secure safety at initial operation of an option device by preventing an excessive increase in the quantity of hydraulic fluids in an initial control section of an option device. A hydraulic circuit of an option device for an excavator comprises a variable capacitance hydraulic pump(26), an option device(24) such as a hammer, a shearer, a breaker, etc. connected to the hydraulic pump, a first spool(15) installed to a flow passage between the hydraulic pump and the option device and converted by the supply of a pilot pressure signal(Pi) to control hydraulic fluids supplied from the hydraulic pump to the option device, a poppet(14) installed to open and close a flow passage(20) between the hydraulic pump and the first spool and controlling hydraulic fluids supplied from the hydraulic pump to the option device when converting the first spool, a piston(13) supported elastically to a back pressure chamber(17) of the poppet by an elastic member(12) such as a compression coil spring, an option spool(25) installed to a flow passage(22) between the first spool and the option device and converted by the supply of a pilot signal pressure to control hydraulic fluids supplied to the option device via the first spool, a second spool(3) converted by a difference between pressure at the inlet side of the first spool, and pressure at the outlet side of the first spool added with elastic force of a valve spring(5) to control hydraulic fluids supplied from the hydraulic pump to the back pressure chamber of the poppet via a flow passage(23) connected with the back flow pressure of the poppet, and a controller installed into the poppet, pressurizing the piston and the poppet by hydraulic fluids supplied from the hydraulic pump when converting the second spool to control hydraulic fluids passing an orifice(14a) of the poppet, and composed of a shim mounted to the inlet side of the orifice of the poppet a provided with a through hole connected with the orifice of the poppet and a check valve installed to the orifice of the poppet and provided with an orifice, a first orifice(13a) formed on the piston to control hydraulic fluids discharged from the hydraulic pump and supplied to the back pressure chamber of the poppet when converting the second spool, a second orifice(30) installed to the flow passage between the second spool and the piston to control hydraulic fluids supplied from the hydraulic pump to the back pressure chamber of the piston when converting the second spool, and a third orifice(31) installed to a flow passage(16) connected to the flow passage between the first spool and the poppet and connected to second spool at the outlet side to control hydraulic fluids discharged from the hydraulic pump to convert the second spool.